OrdinalLogisticBiplot (version 0.4)

plotOrdinalFittedVariable: Function that gives the posibility for the user for plotting in the reduced space an ordered and fitted categorical variable.

Description

Graphical representation of a polytomous ordered variable previously fitted in the reduced space, according to the Ordinal Logistic Biplot theory. It can be choosen some parameters related to the way in which the variable is plotted.

Usage

plotOrdinalFittedVariable(nameVariable, coeffic, D,numFactors, planex = 1, planey = 2,
xi = -3.5, xu = 3.5, yi = -3.5, yu = 3.5, margin = 0,
CexVar = 0.7, ColorVar = "blue",
PchVar = 0.7, addToPlot = FALSE, showIIC = TRUE,
iicxi = -2.5, iicxu = 2.5)

Arguments

nameVariable

Name of the variable the user wants to plot.

coeffic

Vector with the estimated coefficients and the thresholds in this order.

D

Parameter of the graded response model. In case of coefficients have been estimated by Mirt this parameter should be 1.702. In other cases it should be 1.

numFactors

Number of dimensions of the solution

planex

Dimension for X axis.

planey

Dimension for Y axis.

xi

Minimum value on the x-axis.

xu

Maximum value on the x-axis.

yi

Minimum value on the y-axis.

yu

Maximum value on the y-axis.

margin

This value stablishes the space between the plotted items and the border of the window.

CexVar

Size of the category points. It can be an array with the cex information for each variable.

ColorVar

Color for the variables. It can be an array with the color information for each variable.

PchVar

Symbol for the variables. It could be an array with the pch information for each variable.

addToPlot

Boolean parameter to decide if the user wants to add the ordinal variable representation to an existing plot.

showIIC

Boolean parameter to decide if the user wants to see the item information curves for each variable. Default value is FALSE.

iicxi

Lower limit for the X-axis when plotting item information curves.

iicxu

Upper limit for the X-axis when plotting item information curves.

Examples

data(LevelSatPhd)
olbo = OrdinalLogisticBiplot(LevelSatPhd,sFormula=NULL,
      numFactors=2,method="EM",penalization=0.2)
nameVariable="Salary"
coeffic = c(olbo$coefs[1,],olbo$thresholds[1,])
plotOrdinalFittedVariable(nameVariable,coeffic,D=1,numFactors = 2)